In the production of stamped or pressed metal parts, stamping press lines may be supplied with metal blanks that have previously been cut from a metal coil in a separate blanking line. The blanks may be shear-cut metal blanks of a predetermined length or they may be contoured blanks cut with a blanking die.
It is well known the use of industrial loading robots for loading blanks in a stamping press line, such as those for manufacturing vehicle body parts.
In the stamping press lines, the blanks are collected from a stack of blanks by a loading robot which feeds the blanks to the stamping press line. The blanks at the top of the stack e.g. blanks made of magnetic material may be maintained slightly separated from each other at least at the edges, for example by magnets, to prevent them from adhering to each other and thus preventing the loading robot from picking more than one blank, which would cause serious problems in the press.
In recent years, the stamping press lines have been improved and modernized and, therefore, the capacity of the stamping press line to process blanks has been enhanced.
However, the efficiency of the line requires that there is no interruption of the feeding process when the stack is consumed and must thus be replaced by a new stack of blanks. This may lead to undesirable down times in the feeding of the stamping press line.
A known solution in robot lines to avoid down times is providing two stacks of blanks at two different pick-up positions, such that blanks may be taken from one stack, while the other is being replaced.
A problem of this solution may be that the number of loading robots is increased e.g. one robot for each stack of blanks, thus costs may be increased as well. Furthermore, the operative space for each loading robot may be reduced, thus loading robots may be situated in a position far from the pick-up point and therefore, the loading cycle may be slowed down.
In this way, it would be desirable to provide a more flexible solution that allows working with a single stack, and at the same time avoid down times when the stack is exhausted. Furthermore, the number of loading robots may be maintained in a reasonable number.